How to Grow Herbs on a Windowsill: 10 Varieties, Light Minimums and the Harvest-to-Root Ratio
Learn how to grow herbs indoors successfully — best herbs for windowsills, light requirements, watering, harvesting, and solving common problems like leggy growth and fungus gnats.
A kitchen windowsill growing fresh herbs year-round sounds idyllic — and it genuinely is, once you know the few rules that make it work. The problem is that most advice treats all herbs as interchangeable and all windowsills as equally suitable, which is why so many well-intentioned attempts end in a pot of brown basil by February.
The principles are actually straightforward: match your herbs to your light, get watering right (almost always less than you think), harvest in a way that encourages growth rather than stalling it, and use succession sowing for the two herbs that will always bolt on you. This guide covers all of it — from choosing the right herbs for your window orientation to dealing with fungus gnats when they inevitably appear.
Which Herbs Thrive on a Windowsill?
Most windowsill herb kits fail within weeks — not because herbs are fussy, but because the wrong herbs land in the wrong spot with the wrong care. A sunny south-facing ledge and a damp north-facing one are practically different climates, and what thrives in one will struggle in the other.
The good news: once you match the herb to the window and get watering right, a well-chosen indoor herb collection is genuinely low-maintenance. I’ve had a pot of chives on the same east-facing sill for two years — cut back hard in autumn, it just keeps producing. Here’s what works where.
| Herb | Min. Light | Watering | Lifespan | Key Watch-out |
|---|---|---|---|---|
| Basil | 6+ hrs direct sun | Moist, not wet | Annual | Bolts and dies below 10°C |
| Mint | 4–5 hrs (east/west) | Generous | Perennial | Invasive — keep in own pot |
| Parsley | 4–5 hrs | Moderate | Biennial | Slow to establish (3 weeks) |
| Chives | 4–5 hrs | Moderate | Perennial | Cut to 2 cm — regrows reliably |
| Coriander | 5–6 hrs, cool spot | Moderate | Annual | Bolts above 27°C — succession sow |
| Thyme | 6+ hrs direct sun | Sparingly | Perennial | Hates sitting in wet soil |
| Oregano | 5–6 hrs | Sparingly | Perennial | Harvest stems, not single leaves |
Basil
Basil is the most rewarding — and most unforgiving — herb to grow indoors. It demands a south-facing window with at least six hours of direct sunlight daily. Below 10°C, the plant sulks and quickly collapses [4]. In practice, this means winter windowsills are a danger zone: the glass can drop localised temperatures well below the room reading overnight. Move basil to a warm kitchen shelf with a grow light in January and February rather than risking a cold sill.
Water when the top centimetre of soil dries out — basil wants consistent moisture, but waterlogged roots turn its stems to mush within days. For full care detail, see our complete basil growing guide.
Mint
Mint is the most forgiving herb on this list. It tolerates east- or west-facing windows with four to five hours of indirect sun, and it actively likes moisture — it’s one of the few herbs where you don’t need to let the soil dry between waterings. The critical rule: grow it alone. Mint spreads by underground runners and will crowd out everything else in a shared container within a season. Give it its own pot and cut it back hard in autumn to keep it compact.
Parsley
Parsley is slower than people expect. Sown from seed, it takes two to three weeks to germinate and another three weeks before it’s large enough to harvest from. Buy a young plant if you want results quickly. It copes with east- or west-facing windows, tolerates moderate watering, and lasts two years (it’s biennial). Harvest outer stems from the base — this lets the inner rosette keep developing.
Chives
Probably the most foolproof indoor herb. Chives tolerate east- or west-facing windows, cope with occasional drying out, and regrow reliably after cutting. When growth slows in winter, cut the whole pot back to 2 cm above the soil — it will flush back with fresh growth when light returns. Excellent for beginners who want guaranteed results.
Coriander
Coriander is worth growing, but it needs a different strategy to every other herb on this list. It’s a cool-season annual that bolts — redirecting all its energy from leaf to flower — in response to heat and long days. The RHS recommends keeping it in a bright but reasonably cool spot [3]. Above roughly 27°C, bolting is almost inevitable regardless of how you manage the plant. The answer is succession sowing, covered in full below.
Thyme
A Mediterranean herb that evolved on rocky, sun-baked hillsides, thyme needs strong direct light and sharp drainage above everything else. A south-facing window is ideal. Water sparingly — allow the compost to almost fully dry before watering again, and plant in terracotta if possible. Thyme is a woody perennial that will produce reliably for years if you avoid the two things it hates: low light and wet roots.
Oregano
Oregano grows similarly to thyme: sun-loving, drought-tolerant, perennial, and best harvested by the stem rather than individual leaf. It’s slightly more tolerant of lower light than thyme, coping reasonably well in an east-facing window. Harvest regularly — frequent cutting keeps growth compact and productive rather than straggly.
Light: The Single Biggest Factor
Light is where most indoor herb attempts go wrong. “Bright windowsill” sounds simple, but the difference between a south-facing and a north-facing window in a UK winter is the difference between six hours of direct sun and almost none — a chasm that no amount of good compost or careful watering can bridge.
Understanding Your Windows
South-facing — the ideal. In the UK, south-facing windows receive the longest exposure to direct sun, particularly important from October to March when solar angles are low. Basil, thyme, oregano, and rosemary all perform best here.
East- or west-facing — acceptable for less demanding herbs. East windows get morning sun (cooler, ideal for coriander and parsley); west windows get afternoon sun (warmer). Mint, parsley, chives, and coriander can all manage four to five hours of direct sun [5].
North-facing — challenging without supplemental light. Almost no herb produces useful harvests on a north-facing windowsill in winter. Even chives, the toughest of the seven, will grow slowly and produce sparse, pale leaves.
Grow Lights for North-Facing Rooms
If your only indoor space is north-facing, a grow light transforms what’s possible. Penn State Extension recommends running fluorescent or LED lights six to twelve inches above plants for 14 to 16 hours daily as a direct substitute for window light [4].
For practical sizing, Iowa State University Extension provides useful lumen thresholds: herbs need a minimum of around 2,000 lumens per square foot, with 5,000 being comfortable and 7,000 to 7,500 optimal [6]. A single 23-watt CFL bulb producing at least 1,500 lumens works for a small collection of two to three pots; a standard LED shop light (typically 3,500–5,000 lumens) handles a wider spread of six to eight pots easily.
Choose a cool-white bulb (6,000–6,500K colour temperature) — the blue-dominant spectrum promotes compact, leafy growth rather than the stretching and flowering that warmer spectra encourage [6].
Signs your herbs aren’t getting enough light, whether from a window or a grow light that’s too dim or too far away:
- Stems stretch long and thin between leaf nodes (etiolation)
- Leaves are pale green or yellow rather than deep green
- Plants lean heavily toward the light source
- Growth is very slow even in the growing season
If you notice one-sided leaning, the fix is simple: rotate the pot by a quarter turn every few days [5].
Containers, Compost, and Drainage
Getting the Container Right
Container size matters more than most guides suggest. The small plastic pots in windowsill herb kits — typically 6–8 cm diameter — dry out in less than a day in a warm kitchen and force you into daily watering just to keep the herb alive. The stress of constant moisture fluctuation weakens plants and makes them more susceptible to pests.
For individual herbs, aim for pots at least 15 cm (6 inches) in diameter and 15 cm deep. The RHS recommends “long tom” pots — taller than they are wide — for herbs with deep root systems like parsley and rosemary [2]. For window boxes or shared containers, ensure at least 20 cm of depth.
Terracotta vs Plastic
The pot material affects how quickly the compost dries — which in turn determines how often you water and how prone the plant is to root rot or fungus gnats.
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→ View My Garden Calendar- Terracotta: Porous walls allow air to reach roots and moisture to evaporate through the pot, keeping soil drier and roots cooler. Best for drought-tolerant Mediterranean herbs: thyme, oregano, and rosemary. The thermal mass of thick terracotta walls also buffers against sudden temperature swings.
- Plastic: Retains moisture longer and is lighter — practical for mint, parsley, and chives, which prefer more consistent moisture. One caveat: dark-coloured plastic pots placed in strong direct sun can heat the soil significantly, which stresses roots. If you’re using plastic on a south-facing windowsill, choose light-coloured pots.
Whatever material you choose, drainage holes are non-negotiable. Herbs sitting in waterlogged compost — even for 24 hours — are on a path to root rot.
Compost Mix
The RHS recommends John Innes No 1 for most herbs and John Innes No 3 for longer-lived perennials like rosemary, sage, and bay [2]. Both are loam-based and hold their structure well in containers — unlike peat-based multipurpose composts, which compact when dry and take water poorly after drying out.
Add up to 25% coarse horticultural grit or perlite to improve drainage [2]. This is particularly important for thyme and rosemary — even John Innes can hold too much moisture for these herbs without amendment. Mix thoroughly before filling pots.
The Saucer Method
Rather than watering from above and saturating the top layer of soil (which attracts fungus gnats), try the saucer method: place the pot in a shallow saucer, add water to the saucer, and let the roots drink from below. Check after 30 minutes and discard any water the plant hasn’t taken up. This keeps the surface soil drier — exactly the condition that deters fungus gnat egg-laying — while ensuring roots get a proper drink.
Watering Indoors: Less Than You Think
Overwatering kills more indoor herbs than any other cause. The instinct to water daily — because the pot looks dry on the surface, or because you’re invested in the plant — is almost always wrong. Most herb roots need air as much as they need water, and compost kept perpetually wet cuts off that oxygen supply.
The Finger Test
Push your index finger into the compost to the first knuckle (about 2–3 cm). If it feels moist, don’t water. If it feels dry, water thoroughly until it drains from the bottom, then empty the saucer.
The exception is mint, which prefers consistently moist soil — water when the top centimetre dries rather than the full first knuckle.
Signs of Overwatering
- Yellowing leaves, especially lower leaves
- Soft, mushy stems at the base
- A musty or sour smell from the compost
- Wilting despite soil being wet (roots are suffocating)
- Fungus gnats (a near-certain indicator of consistently moist topsoil)
Signs of Underwatering
- Crispy, dry leaf edges and tips
- Compost pulling away from pot sides
- Wilting with dry soil (recovers quickly after watering)
- Leaves curling inward
Water quality rarely matters for most herbs — tap water is fine. Basil can be slightly sensitive to cold water shocking its roots, so use room-temperature water if you’re watering a cold plant from a cold tap in winter.
Feeding Indoor Herbs
Herbs don’t need heavy feeding. The RHS recommends a low-potassium liquid fertiliser applied every two weeks during the growing season [1] — potassium encourages flowering, which you want to avoid (it redirects energy from leaves and reduces flavour). Stop feeding entirely in winter: in low light, herbs grow slowly, and excess nutrients build up in the soil, diminishing aroma and taste [4].
Harvesting: Cut-and-Come-Again
The single most common harvesting mistake is nipping individual leaves. It feels careful and conservative, but it’s actually the least efficient approach — it barely affects growth, and it doesn’t trigger the branching response that makes a plant bushy and productive.
How Cut-and-Come-Again Works
Cutting a stem just above a leaf node (the point where leaves attach to the stem) removes the growing tip and with it the source of auxin — the plant hormone responsible for apical dominance, the tendency of a stem to grow upward rather than branch. Remove that tip, and the two buds in the nodes immediately below it activate and produce two new shoots. Do this repeatedly and a single-stemmed plant becomes a dense, multi-branched bush.
For basil: cut entire stems back to just above a pair of leaves, leaving at least two leaf pairs on the plant. Pinch flower buds the moment they appear — once basil flowers, it puts everything into seed production and leaf quality drops sharply.
For parsley: cut outer stems at the base, allowing the inner rosette to continue developing. Don’t cut from the centre — that’s where new growth originates.
For coriander: cut stems as needed, but accept that mature plants are on a timer. See the succession sowing section below.
Before your first harvest, wait until the plant is established — NC State Extension recommends waiting until there’s enough foliage that removing some won’t stall growth [8]. For most herbs, this means reaching 15–20 cm of height with several sets of leaves. Once established, up to 75% of current growth can be harvested at one time as long as enough leaf is retained for continued photosynthesis [8].
Pruning Woody Herbs
Thyme, rosemary, and oregano have a different structure to basil and parsley: over time, their stems become woody and brown at the base. The critical rule for these herbs is never to cut into old wood — unlike young green growth, woody stems don’t readily produce new shoots from dormant buds.
Always harvest from the soft, new growth at the stem tips, cutting back by no more than one-third. For rosemary, this matters particularly — see our detailed rosemary growing guide for pruning timing and technique. Regular light harvesting through the season keeps these perennials compact and productive for years.
Succession Sowing: The Secret to Year-Round Coriander
Coriander (cilantro) is the herb most people give up on after one failed attempt. It grows beautifully for a few weeks and then — seemingly overnight — shoots up a tall flowering stem, the leaves become small and feathery, and the whole harvest is over. This is bolting, and it’s not a failure of your care. It’s the plant following its biological programming.
Why Coriander Bolts Indoors
Coriander is a cool-season annual. It evolved to germinate in cool autumn or spring conditions, grow quickly, and flower before summer heat arrives. Indoors, it’s responding to the same cues: rising temperature and lengthening daylength. The RHS notes that bolting is triggered by heat, dry conditions, and day length changes [3]. Above roughly 27°C, bolting is essentially inevitable.
You can slow it down — keep coriander away from radiators and south-facing glass in summer, remove flower stems the moment they appear [3], and keep soil consistently moist — but you can’t stop it entirely. The plant will always want to flower.
The Succession Sowing Solution
Rather than fighting the biology, work with it. Treat coriander as a relay crop: sow a small pinch of seeds into a fresh pot every two to three weeks [3]. Space seeds about 5 cm apart. As one batch bolts and becomes unusable, the next is just reaching harvestable size.
This approach works equally well for basil, which bolts in summer heat. Succession sow basil every three to four weeks from March to July and you’ll have a continuous supply rather than one large plant that collapses in August.
The practical setup: keep two or three small pots at different stages. Label each with the sow date. When a pot bolts, compost it and sow a new one in its place. Once you’re in a rhythm, it takes about five minutes every three weeks.
Common Problems with Indoor Herbs
Leggy, Stretched Growth
Cause: Insufficient light. When a plant doesn’t receive enough photons for efficient photosynthesis, it responds by stretching toward whatever light is available — elongating stem internodes in the process. The result is thin, floppy stems with widely spaced leaves.
Fix: Move to a brighter window or add a grow light. There’s no pruning technique that corrects the underlying problem — the plant will keep stretching until light is adequate. Cut leggy stems back hard and improve the light situation simultaneously; the plant will regenerate more compact growth.
Aphids
Aphids can appear on indoor herbs, particularly on basil and mint during warm months. They cluster on new growth and the undersides of leaves, feeding on sap and excreting sticky honeydew. Look for clusters of tiny green, black, or white insects, or leaves that look distorted and curled.
Treatment: Wipe affected leaves with a damp cloth or cotton pad to remove insects manually. For larger infestations, spray with insecticidal soap solution (one part washing-up liquid, ten parts water). Rinse before harvesting and eating. Repeat weekly until clear. Improving air circulation around plants reduces aphid pressure.
Fungus Gnats
Fungus gnats — tiny black flies hovering around your pots — are the most common indoor herb pest, and they’re almost always a sign of consistently moist topsoil.
Understanding the lifecycle helps explain why they’re so persistent. According to Colorado State University Extension, adult females lay up to 200 eggs in the top 2–3 cm of moist compost, and the complete egg-to-adult cycle takes just three to four weeks at typical room temperatures [7]. This means a small initial population can explode quickly in favourable conditions — and the larvae, while small, damage roots and carry root rot pathogens.
Prevention (most effective): Allow the top 2–3 cm of compost to dry between waterings. This single change destroys the habitat that female gnats prefer for egg-laying and kills existing eggs and young larvae through desiccation [7]. The saucer method (watering from below) helps enormously because it keeps surface soil drier.
Monitoring: Hang yellow sticky cards near affected pots. Adults are strongly attracted to yellow, and trapping them reduces the breeding population while showing you how bad the infestation is.
Biological control: For established infestations, apply Steinernema feltiae (parasitic nematodes) as a compost drench — these kill gnat larvae within three to four days and are safe around edible plants [7]. Available from most good garden centres or online.
Indoor Herb Garden Design Ideas
A kitchen herb garden doesn’t need to look like a row of mismatched supermarket pots. With a little thought about arrangement and container choice, a windowsill collection becomes both a productive resource and a genuinely attractive feature.
Tiered Stands
A two- or three-tier wooden or metal plant stand multiplies your growing space without requiring extra window width. Position taller herbs — mint and parsley — at the back on the upper tier, and lower-growing herbs — chives, thyme, and oregano — at the front on lower tiers. This ensures each plant gets light without being shaded by its neighbours. Tiered stands also improve air circulation between pots, which reduces fungal problems on moisture-sensitive herbs.
Window Boxes
A long window box mounted on a deep indoor windowsill lets several herbs share a single planter. The key is matching water needs: thyme, oregano, and chives all prefer moderate to dry conditions and work well together. Avoid mixing mint into a shared box — it will spread aggressively at the expense of neighbours. Keep mint in its own separate container.
Vertical Planters
Wall-mounted pocket planters or hanging vertical systems are useful for small kitchens where windowsill space is limited. They work best with shallower-rooted, compact herbs: chives, oregano, thyme, and small parsley. Avoid basil in very shallow pockets — it needs more root depth to establish well. Water vertical planters carefully, as they dry out faster than standard pots and can drip.
Adding Lavender
For a scented, decorative companion to your culinary herbs, compact lavender varieties work beautifully on a very sunny south-facing sill. Lavender’s edible flowers add a subtle, floral note to biscuits, shortbread, and salads, and its purple spikes contrast attractively with the greens of basil and chives. Our lavender growing guide covers the best compact indoor varieties and care in full.
Frequently Asked Questions
Can I grow rosemary indoors successfully?
Rosemary can be grown indoors, but it has a specific weakness in indoor conditions: low air movement combined with moderate humidity encourages powdery mildew on its needles. A south-facing window with occasional ventilation — a slightly open window on mild days — works well. A grow light on a north-facing kitchen shelf with good airflow is a better option than a stagnant south-facing room. See our complete rosemary guide for full indoor care advice.
Why do windowsill herb kits fail so quickly?
Mainly the pot size. The tiny plastic pots in most kits hold barely any compost, dry out within hours in a warm kitchen, and give roots no room to establish. The resulting stress — daily moisture swings, cramped roots — makes herbs susceptible to every problem from bolting to root rot. Repot into a proper 15 cm container with good compost within a week of buying and the survival rate improves dramatically.
Can I grow herbs year-round without a south-facing window?
Yes, with a grow light. Position an LED grow light 15–30 cm above your herbs and run it for 14 to 16 hours daily. Most common kitchen herbs (basil, mint, parsley, chives, coriander) produce useful harvests under good-quality grow lighting even in north-facing rooms through winter [4][6].
Why is my basil dying in winter?
Almost certainly cold. Basil is a tropical herb that cannot tolerate temperatures below 10°C [4]. A windowsill in a UK January can drop several degrees below the room temperature overnight — particularly if the curtain traps cold air against the glass. Move basil to a warm kitchen shelf, away from the window, and supplement with a grow light.
Can I use garden soil for indoor herbs?
No. Garden soil compacts badly in containers, drains poorly, and routinely introduces pests, weed seeds, and soil-borne pathogens indoors. Use a proper compost — John Innes No 1 for most herbs — with added perlite or coarse grit for drainage [2].
How often should I feed indoor herbs?
During the growing season (roughly March to September), feed every two weeks with a low-potassium water-soluble fertiliser [1][2]. Stop completely in winter — herbs grow very slowly in low light, and accumulating nutrients in the compost reduces flavour and aroma rather than supporting growth.
Sources
- [1] RHS: Herbs — Growing and Harvesting
- [2] RHS: Herbs in Containers
- [3] RHS: Coriander — Grow Your Own
- [4] Penn State Extension: Growing Herbs Indoors
- [5] University of Vermont Extension: Indoor Herb Gardening
- [6] Iowa State University Extension: Supplemental Lighting for Indoor Plants
- [7] Colorado State University Extension: Fungus Gnats as Houseplant and Indoor Pests
- [8] NC State Extension: Harvesting and Preserving Herbs for the Home Gardener
